The gaseous effluents from the manufacturing of semiconductor materials, devices, products and memory articles involves a wide variety of chemical compounds used and produced in the process facility. They contain inorganic and organic compounds, breakdown products of photo-resist and other reagents, and a wide variety of other gases which must be removed from the waste gas streams before being vented from said facility. Typical to the industry, such effluents, either as a single component or multi-component composition, are mixed with an oxidant, such as high purity oxygen, air, nitrous oxide, or other reagents and thermally reacted and/or oxidized at elevated temperatures in a central reaction chamber.
In semiconductor manufacturing processes, various processing operations can produce combustible gas streams. Hydrogen and a variety of hydrides, VOC's, PFC's, HAP's, etc. may be present and, if combined with air, oxygen or other oxidant species such as nitrous oxide, chlorine, fluorine and the like, form reactive mixtures.
However, the composition of the waste gas generated at a workstation may vary widely over time as the successive process steps are carried out. Additionally there are many different wafer process tools with many different recipe chemistries used in typical semiconductor process facilities.
With this variation of the composition of waste gas streams and the need to adequately treat the waste gas on a continuous basis during the operation of the facility, a common approach taken is to provide a single large-scale waste treatment system for an entire process facility. Such systems are almost always over-designed in terms of its treatment capacity, and typically do not have the ability to safely deal with a large number of mixed chemistry streams without posing complex reactive chemical risks. The operating cost associated with heating an extremely dilute mixed gas stream to appropriate elevated temperatures to achieve abatement performance targets is also an issue, in addition to the huge capital cost associated with large scale oxidation units, which often use catalytic chemistry. Furthermore, one of the problems of great concern in gas effluents is the formation of acid mist, acid vapors, acid gases and NOx (NO, NO.sub.2). The present invention provides a method for alleviating the formation of NOx by the appropriate injection of additives into the reactor which not only minimizes or eliminates NOx formation, but also yield less acidic, hence less corrosive effluents.
The present invention provides compact, dedicated units, which may be employed at the point of use. They are designed to serve a single tool, or group of similar chemistry process tools, individual processing operation, or group of abatement compatible process operations to effectively and efficiently remove pollutants without being over-designed with respect to volume capacity, chemical complexity, heat generation and power consumption.